Waveguide-in-waveguide technique involves routing two waveguides through same passageway. Smaller waveguide can be soft or silver soldered inside X-band waveguide to form single ridge guide and to propagate frequencies at C-band

Franke, J. M.

English

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o	 0 
0.900 in. 
F(2.286 cm) 'l 
-I LL	 'lu g ii 1E4±II 
_0 0
0.140 In. 
(0.356 cm) 
0.400 In. 
(1.016 cm)
June 1975	 B75-10091 
NASA TECH BRIEF 
Langley Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
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be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Dual-Band Ridged Wavegulde 
A ridged waveguide is often considered in a design 
when extremely wide bandwidths are required and a 
system cannot tolerate the losses inherent in a coaxial 
cable or a microstrip. Such a waveguide is expensive 
to machine and generates considerable material waste 
in manufacture, but a new "waveguide-in-waveguide" 
technique overcomes such drawbacks and also 
provides the needed results. It involves the routing of 
two waveguides through the same passageway. A 
smaller waveguide, such as a WR-28 millimeter 
waveguide, can be soft or silver soldered inside an 
X-band waveguide (WR-90) to form a single ridged 
guide and to propagate frequencies at the C-band. 
The ridged waveguide may have a central ridge 
added to the top or the bottom, or both, of a 
rectangular section. This lowers the cutoff frequency 
of the guide due to the capacitive effect at the center.
In principle, the cutoff frequency may be made as low 
as desired by decreasing the gap width (g in the 
illustration) sufficiently. Impedance decreases, how-
ever. 
For example, by inserting the WR-28 waveguide 
(which covers 26.5 to 40 GHz) into the WR-90 
waveguide (8.2 to 12.4 GHz), the cutoff frequencies of 
the outer guide then become approximately 4.5 GHz 
and 11.2 GHz. It can be used for frequencies from 7 
through 10 GHz and should be usable well down into 
the C-band before attenuation effects become severe. 
The characteristics of the inner guide are unaltered. 
A method to decouple the guides is shown in the 
illustration. The smaller WR-28 guide continues 
through the end wall of the larger guide, and a 
coaxial-to-waveguide adapter is used to couple energy 
from the outside guide. 
0.280 in. 
(0.711 cm) 
Dual-Band Ridged Wavegulde
(continued overleaf) 
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https://ntrs.nasa.gov/search.jsp?R=19750000091 2020-03-19T20:07:13+00:00Z
Note:	 Patent status: 
No further documentation is available. Specific 	 Inquiries concerning rights for the commercial use 
questions, however, may be directed to: 	 of this invention should be addressed to: 
Technology Utilization Officer	 Patent Counsel 
Langley Research Center	 Langley Research Center 
Mail Stop 139-A	 Mail Stop 313 
Hampton, Virginia 23665 	 Hampton, Virginia 23665 
Reference: B75-10091
Source: John M. Franke
Langley Research Center
(LAR-11781)
S 
Categories: 01 (Electronics - Components 
and Circuitry) 
875-10091	 02 (Electronics Systems)


Dual-band ridged waveguide

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